Apache2 Proxy wrong routing - apache

Question

I use apache2 as a proxy to distribute request for different URLs to different lxc containers on ubuntu 16.04 LTS
For example:
www.adomain.com is proxied to 10.0.3.100
www.bdomain.com is proxied to 10.0.3.101
etc.
In principle this works but fine, but now I see a strange behaviour.
Config file bbb.adomain.com:
<VirtualHost bbb.adomain.com:80>
ServerName bbb.adomain.com
ProxyRequests Off
ProxyPreserveHost On
<Proxy *>
Order deny,allow
Allow from all
</Proxy>
ProxyPass / http://10.0.3.104/
ProxyPassReverse / http://10.0.3.104/
<Location />
Order allow,deny
Allow from all
</Location>
</VirtualHost>
This works fine, every request for bbb.adomain.com ist proxied to 10.0.3.104
However, also requests to xxx.bdomain.com are proxied to 10.0.3.104, too. But xxx.bdomain.com is NOT configured as virtual host / servername in ANY apache .conf file.
How can I configure apache2, that any URL which is not configured as virtual host / servername is NOT proxied?
How can I debug apache2 to find out, why this domain xxx.bdomain.com is proxied?
By the way - the first apache config file is 000.conf:
<VirtualHost *:80>
ServerName catchall
<Location />
Order allow,deny
Deny from all
</Location>

Answer 1

You can try this basic configuration :
<VirtualHost *:80>
ServerName bbb.adomain.com
ProxyRequests Off
ProxyPreserveHost On
<Proxy *>
Order deny,allow
Allow from all
</Proxy>
ProxyPass / http://10.0.3.104/
ProxyPassReverse / http://10.0.3.104/
<Location />
Order allow,deny
Allow from all
</Location>
</VirtualHost>
<VirtualHost *:80>
ServerName xxx.bdomain.com
DocumentRoot /var/www/example
</VirtualHost>

Answer 2

Using the following steps:
1) Update virtual file:-
<VirtualHost *:80>
ServerAdmin admin#test.com
ServerName mysite.com
ServerAlias www.mysite.com
ProxyRequests Off Order deny,allow Allow from all
<Location />
ProxyPass http:// mysite.com:8000/
ProxyPassReverse http:// mysite.com:8000/
</Location>
</VirtualHost>
2) Enabling Necessary Apache Modules
To enable these four modules, execute the following commands in succession.
sudo a2enmod proxy
sudo a2enmod proxy_http
sudo a2enmod proxy_balancer
sudo a2enmod lbmethod_byrequests
3) To put these changes into effect, restart Apache.
sudo systemctl restart apache2